I'm certainly pleased you included unit tests, I'm just wondering whether we can avoid adding another dependency. :)

Mocha allows asynchronous tests to be run synchronously. I imagine the tests would take the following form:

```coffeescript
{exec} = require 'child_process'

describe 'tutor.command', ->

  it 'does something...', (done) ->
    exec 'bin/tutor ...', (err, stdout, stderr) ->
      ... # perform checks
      done() # tell Mocha to run the next test
```